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Thin cathodes for thermal batteries with good homogeneity and a reproducible thickness were prepared using a tape-casting process. A single cell fabricated with a 100 µm thick cathode using tape-casting process exhibited a specific capacity of 1934.08 A s/g. In contrast, a single cell fabricated with a pellet type 500 µm thick cathode demonstrated a specific capacity of 1000.25 A s/g. The thin cathode, which exhibited excellent utilization of the electrode material due to the optimal thickness from an electrochemical point of view, showed good mechanical strength and excellent electrochemical properties making it suitable for use in thermal batteries.

The use of a thermally and chemically stable ceramic felt separator for thermal batteries is believed to enhance the reliability by minimizing the sudden failure of an electrolyte upon shock compared to the conventional pellet-pressed one. To achieve desirable electrochemical properties for applications in thermal batteries, the separator should hold a sufficient amount of molten electrolyte with a minimal leakage to prevent physical contact between the cathode and anode. In addition, the chemical stability of the separator materials should be maintained under a very reactive molten Li-salt electrolyte environment to confer high ionic conductivity and reliability. To assess the feasibility of 3 types of ceramic felt as a separator for thermal batteries, 2 types of Al2O3 felt with different porosity and one ZrO2 felt are examined using binary LiCl-KCl and ternary LiF-LiCl-LiBr as the electrolytes. This Part 1 explains the wetting, loading and leakage behaviors of the ceramic felts for molten electrolytes along with the chemical stability. The ionic conductivity of the electrolytes and electrochemical properties of the resulting thermal batteries will be presented in Part 2.

In this study, we fabricated a cathode with lower amounts of additive materials and higher amounts of active materials than those of a conventional cathode. A thermal battery was fabricated using FeS2 treated foam as the cathode frame, and its feasibility was verified. X-ray diffraction, transmission electron microscopy, and scanning electron microscopy were used to analyze the effects of thermal sulfidation temperature (400 and 500°C) on the structure and surface morphology of the FeS2 foam. The optimal temperature for the fabrication of the FeSx treated foam was determined to be 500°C. The FeS2 treated foam reduced the interfacial resistance and improved the mechanical strength of the cathode. The discharge capacity of the thermal battery using the FeS2 treated foam was about 1.3 times higher than that of a thermal battery using pure Fe metal foam.

The polymer binder, poly(imide-co-siloxane) (PIS), was synthesized and applied to form a thin cathode layer composites for a thermal battery that has an unusually high operating temperature of 450 °C. The PIS was prepared through cross-linking of the polyimide with polysiloxane. The morphology of FeS2/PIS composites showed that FeS2 particles was coated with the PIS cross-linked gel. The FeS2/PIS composites enabled to fabricate mechanically stable thin cathode layer that was 20–10% of the thickness of a conventional pellet-type cathode. The FeS2/PIS composites were stable up to 400 °C and maintained their morphology at this temperature. PIS coating layers decomposed at 450 °C and a new residue was generated, which was observed by transmission electron microscopy and the compositional change was analyzed. The FeS2/PIS composites showed enhanced thermal stability over that of FeS2 in thermogravimetric analysis. The thermal battery with the PIS polymer binder showed a 20% discharge capacity increase when compared to a conventional pellet-type cathode.

The three-dimensional (3D), nitrogen doped reduced graphene oxide (N-RGO) monoliths have been synthesized using graphene oxide and melamine through an ice-templated assembly. The self-assembled monoliths are accompanied with the considerable reduction of graphene oxide after annealing and specific surface area of 190 m 2 g −1 . The blue shift of approximately 22 cm −1 and 4 cm −1 in D and G bands for N-RGO is notified in Raman analysis, confirming the incorporation of nitrogen onto the graphene sheet. In addition, an extra peak at 1251 cm −1 appears possibly due to the stretching vibration of C–N bonds. The detailed doping configurations analyzed by x-ray photoemission spectroscopy indicate the nitrogen content of around 6.2 at% in the N-RGO with predominant pyridinic N-type configuration. The specific capacitance is enhanced up to 217 F g −1 at a scan rate of 5 mV s −1 , which is approximately three times higher than that of the pristine 3D RGO owing to the pseudocapacitive behavior of N-RGO. The high electronic conductivity of the N-RGO electrode with low charge transfer resistance as confirmed by electrochemical impedance spectroscopy is associated with good rate capability. Furthermore, the N-RGO sample exhibits an excellent cyclic stability with no decay in capacitance even after 5000 cycles at scan rate of 100 mV s −1 .

Micro/meso-porous reduced graphite oxide (MMRGO) nanosheets were produced using precursor carbide-derived carbon (CDC), which was produced at a high temperature of 1200 °C, through a massive wet chemistry synthetic route involving graphite oxidation and microwave reduction. X-ray diffraction (XRD) and transmission electron microscopy (TEM) show that the MMRGO nanosheets were fabricated with 2–3 layers and ripple-like corrugations. N2 sorption isotherms confirmed that micro/meso-pores coexisted in the RGO sample from CDC. In the anode application of Li-ion batteries, this RGO sample had an enhanced capacity performance at the 0.1 C rate and 1 C rate, with ∼1200 mAh g−1 at the 100th cycle and ∼1000 mAh g−1 at the 200th cycle, respectively.

has been widely used for cathode materials in thermal battery because of its high stability and current capability at high operation temperature. Salts such as a LiCl-KCl were added as a binder for improving electrical performance and formability of cathode powder. In this study, the effects of the addition of in LiCl-KCl binder on the formability of powder compact were investigated. With the increasing amount of addition to LiCl-KCl binder salts, the strength of the pressed compacts increased considerably when the powder mixture were pre-heat-treated above . The heat-treatment resulted in promoting the coating coverage of particles by the salts as was added. The observed coating as addition might be attributed to the enhanced wettability of the salt rather than its reduced melting temperature. The high strength of compacts by the addition and pre-heat-treatment could improve the formability of raw materials.

Thermal batteries have excellent mechanical robustness, reliability, and long shelf life. Due to these characteristics as well as their unique activation mechanism, thermal batteries are widely adopted as military power sources. Li(Si)/ thermal batteries, which are used mostly in these days, use LiCl-KCl and LiBr-LiCl-LiF as molten salt electrolyte. However, it is known that Li(Si)/ thermal batteries have high internal resistance. Especially, cathode accounts for the greater part of internal resistance in unit cell. Many efforts have been put into to decrease the internal resistance of thermal batteries, which result in the development of new electrode material and new electrode manufacturing processes. But the applications of these new materials and processes are in some cases very expensive and need complicated additional processes. In this study, internal resistance study was conducted by adding carbon black and carbon nano-tube, which has high electron conductivity, into the cathode. As a results, it was found that the decrease of internal resistance of cathode by the addition of carbon black and carbon nano-tube.

We have tried to develop a lithium/thionyl chloride reserve battery (560W). A cell consists of 5 double-sided cathodes and anodes (toroidal shape, electrode area: 100 cm2, cell surface area: 900 cm2, current density: 22mA/cm2). We have designed a unique internal serial connection, which is capable of obtaining a desired voltage by simply stacking the cells and then tightening the internal serial connection volts. A piston-type electrolyte reservoir is designed. Our dual-piston electrolyte reservoir requires smaller space for the piston movement than a single-piston reservoir. It also renders reliable opening of the diaphragm, and appropriate electrolyte transferring speed to avoid damage to the carbon electrodes. The batteries underwent performance tests, environmental tests, and accelerated aging test.

The direct formation of CN and CO bonds from inert gases is essential for chemical/biological processes and energy storage systems. However, its application to carbon nanomaterials for improved energy storage remains technologically challenging. A simple and very fast method to form CN and CO bonds in reduced graphene oxide (RGO) and carbon nanotubes (CNTs) by an ultrasonic chemical reaction is described. Electrodes of nitrogen- or oxygen-doped RGO (N-RGO or O-RGO, respectively) are fabricated via the fixation between N2 or O2 carrier gas molecules and ultrasonically activated RGO. The materials exhibit much higher capacitance after doping (133, 284, and 74 F g-1 for O-RGO, N-RGO, and RGO, respectively). Furthermore, the doped 2D RGO and 1D CNT materials are prepared by layer-by-layer deposition using ultrasonic spray to form 3D porous electrodes. These electrodes demonstrate very high specific capacitances (62.8 mF cm-2 and 621 F g-1 at 10 mV s-1 for N-RGO/N-CNT at 1:1, v/v), high cycling stability, and structural flexibility.